Composite sewage tank

ABSTRACT

This invention comprises a settling tank of the type in which is incorporated a built-in settling trough or chamber. The invention also includes within its scope an improved process of building such tanks with precast panels in accordance with sound engineering practice and in a manner that is advantageous from the standpoint of expense and durability.

United States Patent 1 1 1111 3,804,260 I Crowley Apr. 16, 1974 COMPOSITE SEWAGE TANK 2,854,146 9/1958 Nebolsine et al. 210/525 [75] Invent! Francis Cmwleyi wenesley, 1,324,522 85:33; 12 332110 52/ 3 5 1: Mass- 3,612,470 10/1971 Car 52/73 Assignee: Crowley Hession Engineers, 2,569,669 10/1951 Henderson 52/283 Wakefield, Mass. Primary Examiner- -Charles N. Hart [22] led: 1971 Assistant Examiner-T. A. Granger [21] Appl. No.: 209,724 Attorney, Agent, or Firm-Kenway, Jenney & Hildreth [52] U.S. Cl 210/513, 52/73, 52/224 [57] ABSTRACT [51] Int. Cl 80111 21/00 This invention comprises a settling tank of the type in which is incorporated a built-in settling trough or chamber. The invention also includes within its scope an improved process of building such tanks with pre- 1561 32:12:21,;zstzsmzzsm zz'zs UNITED STATES PATENTS the standpoint of expense and durability.

1,357,587 11/1920 Peck 3,408,784 l1/196 8 Crowley 52/224 5Claims,4l)rawlng Figures [58] Field of Search 210/513-528; 52/224, 264, 745, 586, 332, 333, 341, 338, 419, 73, 245, 246, 283

memenm 16 m4 3.804260 SHEET' 1 OF 2 FIG. 2

INVENTORS ATTORNEYS 1 COMPOSITE SEWAGE TANK The tank of this-invention may be constructed of panels precast and initially assembled in circular or other closed formation with upright longitudinal channels or slots located between adjacent panels or spaced with respect to certain of them. These channels are subsequently filled and closed from top to bottom of the tank with cement or mortar and at an intermediate level certain panels contain inwardly projecting cantilever spoke sections or kneesrThese corbel units act collectively as fully efficient brackets upon which may now u be supported a circularsettling chamber or trough. The inner wall of thistrough forms a circular weir over which the liquid effluent flows into the trough. The corbel units may be cast at any selected level within the tank'with the assistance of temporary forms. The bot.- tom and side wall or walls of the effluent trough may be readily cast upon the firm foundation of the corbels.

The effluent trough may be formed in part by thecore wall of the tank itself or it may be located at a distance from the inner tank wall so that weir overflow takes place at both circumferential walls of the trough.

The panels may be precast-upon metal sheathing as described in-my prior U.S. Pat.No. 3,280,525 Oct. 25, l966. The tank as a whole may be prestressed by winding with wire ormetal cable in position to enclose the corbel units and finally a cemetitious cover coating for the prestressing wire may be applied.-

A feature of the invention'in which sound engineering principles of concrete construction are put into effeet 'is achieved by employing cantilever sections inclined inwardly and upwardly in cone-like arrangement within the v tank. In such a construction the entire weight of the effluent trough and its'liquid contents are transmitted as compression to the corbel spokes. Thus both the spokes and the effluent-trough are maintained in a state of continuous compression.

These and other features of the invention will be more readily understood from the following description of preferred embodiments thereof, selected for purposes of illustrationa'nd shownin the accompanying drawings, in which I FIG. I is a view in perspective of a quarter section of the core wall, r 7

FIG. 2 is a fragmentary sectional view of the wall,

FIGS. 3 and 4 are corresponding views of a modified tank construction.

In the tank of FIGS. 1 and 2 each panel is represented as precast upon metal sheathing 11 which forms the outer surface of the precast core wall. These panels 10 are assembled and erected to form the cylindrical core wall of the tank, and may be located underground in an adequate excavation.

In assembling the panels 10 open channels 12 are dispersed between them-for the reception of corbel units.

corbel units include cantilever sections which incline inwardly and upwardly in the tank' giving the whole assembly the resemblance of a shallow upwardly convex 2 cone. It is apparent therefore that the full weight of the trough is supported as compression by the cantilever section of the corbel units. This pressure therefore subjects the arms to continuous pressure above anything encountered in the operation of the tank.

The effluent trough is completed by an inner wall 17 which acts as an inlet weir for the trough. As shown in FIGS. 1 and 2 the outer wall of the trough is formed by the inner surface of the core wall of the tank while the inner wall 17 of the trough may be cast integral with the bottom 16. At a convenient place the trough may be provided with an outlet pipe 30 through which the contents of the trough may be drained for further treatment without encountering disturbance that would tend to float the solid contents of the effluent.

-In FIGS. 3 and 4 is illustrated a tank of modified construction in which the effluent trough as a whole is offset inwardly and spaced with respect to the'core wall so that the outer wall 29.will serve as an additional inlet weir, thus substantially increasing the weir length as compared to that of the tank shown in FIGS. 1 and 2.

- The panels 20 are separated by channels 22 which are later filled with solidified corbel units 23. Each corbel unit is provided with a spoke25 extending upwardly and inwardly to the bottom of the effluent trough 27. The effluent trough is completed by an inner wall 28 and an outer wall 29. The trough is provided at a convenient location with an outlet pipe 30 by which the effluent may be drained from the trough. The clamping section 24 is extended upwardly to a ring or flange which retains the trough is true concentric location. The lower ends of the spokes 25 extend to the core wall near the bottom of thetank and are confined by binding with prestressed wire 32 which thus is arranged to confine the outward pressure transmitted by the spokes 'It is apparent that by locating the assembled conelike structure at a convenient height above the footing 31 of the core wallthe bottom of the tank'is left entirely free of obstructions that would hinder the free passage of a sludge scraper or plow rotating on the floor of the tank.

The coil of wire 32 forms a ten'sion band embracing the outer ends of the corbel spokes, while the flange or ring 32 forms a compression band embracing the upper ends of the spokes.

The corbel units may be of any desired width.'ln fact they may be of the full width of the panels 10, although a width of 12 to '14 inches is usually adequate and more convenient for construction of a tank upon its permanent site. I

I claim:

I. A settling tank having an outer circular wall of precast concrete panels, cast-in-place concrete filler joints between said panels, said wall being constructed and arranged upon a floor for said tank, metal tension members encircling the exterior of said circular wall, concrete structural members each with a first end and a second end supporting an effluent trough within said tank, said first end of each said structural member being connected to a filler'joint and integral therewith, said structural members being inclined inwardly and upwardly whereby said second ends are higher than said-first ends whereby the weight of the trough is transmitted to the structural members to place said structural members in compression.

2. A settling tank as described in claim 1., wherein the effluent trough has inner and outer walls which are spaced from the inner surface of the wall sufficiently for both the inner and the outer walls of the trough to act as weirs.

3. A settling tank as described in claim 1, wherein the effluent trough is mounted concentrically within the wall of the tank by said concrete structural members under compression having inwardly and upwardly inclined sections confined at their upper ends by the pression. 

1. A settling tank having an outer circular wall of precast concrete panels, cast-in-place concrete filler joints between said panels, said wall being constructed and arranged upon a floor for said tank, metal tension members encircling the exterior of said circular wall, concrete structural members each with a first end and a second end supporting an effluent trough within said tank, said first end of each said structural member being connected to a filler joint and integral therewith, said structural members being inclined inwardly and upwardly whereby said second ends are higher than said first ends whereby the weight of the trough is transmitted to the structural members to place said structural members in compression.
 2. A settling tank as described in claim 1, wherein the effluent trough has inner and outer walls which are spaced from the inner surface of the wall sufficiently for both the inner and the outer walls of the trough to act as weirs.
 3. A settling tank as described in claim 1, wherein the effluent trough is mounted concentrically within the wall of the tank by said concrete structural members under compression having inwardly and upwardly inclined sections confined at their upper ends by the trough in a state of compression and at their lower ends by a tension ring.
 4. A settling tank as described in claim 3, wherein the tension ring at the lower ends of the inclined sections is prestressed.
 5. The tank of claim 2 in which the trough and said concrete structural members are maintained in compression. 